This section provides background information related to the present disclosure which is not necessarily prior art.
The device according to the preamble comprises a machine stand which comprises a support surface for a flat workpiece, wherein the support surface is formed by at least one counterholder, on the front face of which the workpiece can be placed. The device moreover comprises a hold-down unit, by means of which the tool is pressed against the support surface, as well as a processing head which can moved relative to the support surface for the machining of the workpiece.
From DE 100 11 754 A1, a device for low-vibration clamping of flat workpieces on a machining apparatus is known. The machining apparatus comprises a machine stand with a support surface for the tool, which extends preferably substantially vertically, as well as with a bridge with a processing head, which can be moved relative to the support surface for the machining of the workpiece. On the bridge, at least one hold-down unit is attached, which is used to press the workpiece as it is being processed against the support surface which is formed by a plurality of support bolts connected by plug connection to the machine stand and preferably made of plastic, which are distributed according to a predetermined arrangement on the machine stand. In order to prevent vibrations which can be generated when a tool, for example, a milling cutter, is moved through the workpiece, it is proposed that the hold-down unit moreover comprises a pressing device with a spring element which prestresses a pressing arm in the direction of the support surface.
In the device known from DE 100 11 754 A1, the workpiece is thus placed on columnar support bolts which form counterholders and against which the flat workpiece is braced by means of the hold-down unit. It was observed that, in spite of the spring elements in the hold-down units, the workpiece can vibrate strongly when the tool, for example, a shank rough milling cutter, is passed through the workpiece. These vibrations decrease the cutting performance and the useful life of the tool. In addition, they cause considerable noise emission.